Preparation of e.g. injectable medications and intravenous solutions requires a high sterility level to reduce or eliminate the risk of exposing persons and animals to microorganisms, such as bacteria and viruses. A widely used device for sterilization of pre-filled containers is the so called ventilator or steam/air autoclave. Ventilator autoclaves are autoclaves where air is kept in the sterilization chamber during the process, unlike traditional steam sterilizers in which air is removed before sterilization. The purpose of maintaining air in the sterilization chamber is to provide a supporting pressure that assists in avoiding deformation of the containers.
Known ventilator autoclaves often comprise a sterilization chamber, a fan for circulating the steam/air in the chamber and heat exchangers for heating/cooling the steam/air. The fan may e.g. be a centrifugal fan and is often installed at the top of the sterilization chamber. The heat exchangers are commonly placed along the side walls of the chamber, behind internal panels that creates a duct between the internal panel and the autoclave wall. By this, a circulating environment is created in which the fan directs steam/air towards the heat exchangers. When steam/air passes the heat exchangers it is heated or cooled, depending on the phase of the sterilization process, before it is directed towards the goods in the autoclave.
In general terms, the sterilization process is carried out in the following manner. The goods to be sterilized, e.g. in the form of pre-filled plastic syringes, containers and vials comprising liquid, gel-like or paste-like pharmaceutical or biological products are typically placed in the autoclave. Heating liquid may then optionally be supplied to the heat exchangers so that the air in the autoclave becomes heated and pre-heats the goods to be sterilized. Thereafter, the goods to be sterilized is subjected to steam until the temperature reaches about 121° C. This temperature is maintained for a time sufficient to sterilize the content. As the prefilled container is heated, the fluid or formulation contained therein vaporizes. The vapor produces a pressure and temperature which is lethal or cidal to pathogens. Following sterilization, the pre-filled containers are subjected to a cooling step. During the cooling step, cooling liquid is supplied to the heat exchangers, which in turn cool the steam/air in the autoclave.
The known ventilator autoclaves are known to function well. However, as in many industrial processes, there are economic benefits if the sterilization process may be carried out faster. Hence, it is an object of the present invention to suggest an improved ventilator autoclave that may be able to carry out the sterilization process faster than known autoclaves.